U.S. patent number 4,621,552 [Application Number 06/689,078] was granted by the patent office on 1986-11-11 for method and apparatus for separating printed-circuit boards from multi-board panels.
This patent grant is currently assigned to Cencorp. Invention is credited to Gilbert T. Lopez.
United States Patent |
4,621,552 |
Lopez |
November 11, 1986 |
Method and apparatus for separating printed-circuit boards from
multi-board panels
Abstract
The instant invention is particularly directed to a method and
apparatus for automated handling of panels comprising a plurality
of interconnected substrates in order to control and separate the
circuit boards in a continuous processing line. One embodiment
incorporates two shearing stations and a rotary transfer device
therebetween in order to transfer a panel portion from the first
station to the second station while controlling and rotating the
panel for subsequent feed to the second station such that the panel
portion is cut on a line of the substrate which is perpendicular to
the original line of cut of the substrate. Throughout the handling
of the panels and panel portions, sensing, gripping, and indexed
feeding of the panels and panel portions are under the control of a
programmable computer.
Inventors: |
Lopez; Gilbert T. (Longmont,
CO) |
Assignee: |
Cencorp (Boulder, CO)
|
Family
ID: |
24766959 |
Appl.
No.: |
06/689,078 |
Filed: |
January 4, 1985 |
Current U.S.
Class: |
83/27; 83/104;
83/206; 83/250; 83/277; 83/33; 83/35; 83/360; 83/62; 83/76.8;
83/929.1 |
Current CPC
Class: |
B26D
7/015 (20130101); B26D 11/00 (20130101); H05K
3/0052 (20130101); B26D 7/0675 (20130101); Y10T
83/445 (20150401); B26D 2007/0056 (20130101); H05K
2203/0228 (20130101); Y10T 83/0505 (20150401); Y10T
83/088 (20150401); Y10T 83/0495 (20150401); Y10T
83/178 (20150401); Y10T 83/0467 (20150401); Y10T
83/4632 (20150401); Y10T 83/4564 (20150401); Y10T
83/2081 (20150401); Y10T 83/525 (20150401) |
Current International
Class: |
B26D
11/00 (20060101); B26D 7/06 (20060101); B26D
7/01 (20060101); H05K 3/00 (20060101); B26D
005/26 () |
Field of
Search: |
;83/33,206,207,277,278,415,423,522,104,71,360,62,250,35,27
;269/50-52,47 ;198/692,693 ;271/84,85,141 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Meister; James M.
Attorney, Agent or Firm: Fidelman, Wolffe & Waldron
Claims
What is claimed is:
1. A method of handling a panel automatedly, said panel having
means for referencing positional control of said panel, and
comprising the steps of:
receiving said panel at a feed assembly input;
searching for said panel referencing means;
clamping said panel according to and upon locating said referencing
means;
feeding said panel, while clamped, to a processing station and
indexing said feeding according to a controller; and
subdividing said panel at said processing station according to said
controller.
2. A method as in claim 1, and further comprising the steps of;
positioning said panel against a reference surface for subsequent
locating of said panel referencing means during said searching;
and
verifying proper clamping of said panel prior to said feeding.
3. A method as in claim 1, and further comprising the step of:
aligning said panel by said clamping.
4. A method as in claim 1, and further comprising the steps of:
identifying said panel according to a particular configuration;
and
selecting a particular control routine for said controller
according to said identifying.
5. A method as in claim 1, wherein said subdividing comprises the
step of:
separating at least one circuit board from said panel.
6. A method as in claim 5, and further comprising the step of:
cutting said panel to effect said separating.
7. A method as in claim 6, and further comprising the step of:
shearing said panel to effect said cutting.
8. A method as in claim 6, wherein said circuit board has component
leads protruding from a lower surface thereof, and further
comprising the step of:
displacing said circuit board relative to a cutting member at said
processing station in order to provide clearance between said leads
and said cutting member during said feeding.
9. A method as in claim 5, wherein said panel further comprises at
least one scrap portion, said method further comprising the steps
of:
receiving said circuit board from said processing station; and
diverting said scrap portions to a scrap pile.
10. A method as in claim 9, wherein said clamping is performed by a
clamping means on a final scrap portion of said panel, and further
comprising the steps of:
unclamping said final scrap portion; and
propelling said final scrap portions from said clamping means.
11. An apparatus for handling a panel automatedly, said panel
having means for referencing positional control of said panel, and
comprising:
means for receiving said panel at a feed assembly input;
means for searching for said panel referencing means;
means for clamping said panel according to and upon locating said
referencing means;
means for feeding said panel, while clamped, to a processing
station and indexing said feeding according to a controller;
and
means for subdividing said panel at said processing station
according to said controller.
12. An apparatus as in claim 11, and further comprising:
means for positioning said panel against a reference surface for
subsequent locating of said panel referencing means during said
searching; and
means for verifying proper clamping of said panel prior to said
feeding.
13. An apparatus as in claim 11, and said clamping means further
comprising:
means for aligning said panel during said clamping.
14. An apparatus as in claim 11, and further comprising:
means for identifying said panel according to a particular
configuration; and
means for selecting a particular control routine for said
controller according to said identifying.
15. An apparatus as in claim 11, and further comprising:
means for separating at least one circuit board from said panel to
effect said subdividing.
16. An apparatus as in claim 15, and further comprising:
means for cutting said panel to effect said separting.
17. An apparatus as in claim 16, and further comprising:
means for shearing said panel to effect said cutting.
18. An apparatus as in claim 16, wherein said circuit board has
component leads protruding from a lower surface thereof, and
further comprising:
means for displacing said circuit board relative to a cutting
member at said processing station in order to provide clearance
between said leads and said cutting member during said feeding.
19. An apparatus as claim 15, wherein said panel further comprises
at least one scrap portion, and further comprising:
means for receiving said circuit board from said processing
station; and
means for diverting said scrap portions to a scrap pile.
20. An apparatus as in claim 19, wherein said clamping is performed
by a clamping means on a final scrap portion of said panel, and
further comprising;
means for unclamping said final scrap portion; and
means for propelling said final scrap portion from said clamping
means.
Description
CROSS-REFERENCES TO PRIOR ART
U.S. Pat. No. 3,780,431--Feeney--PROCESS FOR PRODUCING COMPUTER
CIRCUITS UTILIZING PRINTED CIRCUIT BOARDS.
U.S. Pat. No. 4,316,320--Nogawa, et al.--METHOD OF MANUFACTURING
ELECTRONIC CIRCUIT APPARATUS.
U.S. Pat. No. 4,343,083--Takamura, et al.--METHOD OF MANUFACTURING
FLEXIBLE PRINTED CIRCUIT SHEETS.
U.S. Pat. No. 4,426,773--Hargis--ARRAY OF ELECTRONIC PACKAGING
SUBSTRATES.
BACKGROUND OF THE INVENTION
Substantial savings of time and money have been realized in the
industry by handing a plurality of printed circuit boards (PCB's)
while they are still interconnected in a panel of substrate
material. Better utilization is realized with this approach in such
processing as population of the PCB's with components, wave
soldering of the populated boards, and quality control such as
electrical function testing of whole boards or selected components,
particularly when considering the automated processing demands of
today's industry.
Methods for enabling separating of each prepopulated panel into
plural, individual PCB's include: routing with tabs; scoring;
perforation; and punch-back.
Routing with tabs comprises routing slots in the panel (while
leaving spaced support tabs) to define the perimeters of the
individual boards, so that the tabs may be cut or broken in order
to perform board separation.
Scoring comprises grooving board perimeters on at least one side of
the panel in order to effect board separation by breaking along the
score-lines.
Perforation comprises drilling a series of closely spaced holes in
the panel along the board perimeters so that board separation is
performed by breaking along the lines of perforations.
The punch-back method utilizes a custom-made die to punch each
board out of the panel and then pull it back into the panel so
that, after population, the boards are easily pushed from the
panel.
All of these "break-away" methods of preparing panels, for
subsequent separation of the populated PCB's, inherently rob the
panel of its rigidity. Consequently, the panels are prone to:
sagging during wave soldering; excessive warping; and premature
breakage. Moreover, methods incorporating excessive treatment by a
router are expensive, can permit solder to overflow onto the
component side of the panel during wave soldering, and often can
require a secondary procedure for removing tab stubs. Perforation
and scoring yeild poor quality edges and cannot hold close
tolerances. Punch-back methods require expensive tooling and cannot
process zero-spaced configurations, i.e., panels without scrap
strips between adjacent circuit boards. Premature separation during
panel handling is frequently encountered with the punch-back and
scoring methods.
Whether or not the boards have been populated, high precision
shearing is recognized as a preferred, cost-effective method for
PCB profiling by separating individual boards from the panels. The
shock to delicate components and traces, normally encountered
during the separating of boards from panels by breaking along
perforation or score lines, can be obviated by shearing blade
configurations. Further, a panel may be gently sheared without the
shock of other methods, while providing excellent edge quality and
holding board perimeter tolerances within 0.005 inches, repeatedly.
Since there are no tab stubs to be removed with the shearing
method, the circuit boards often can be zero-spaced (without waste
strips) in order to provide more boards per panel. In fact, many
rectangular boards can be sheared in less time than it takes to cut
the same run with an NC router, while irregular boards can be cut
by combining the routing and shearing methods to minimize the
routing and maximize panel rigidity. The clean, simple edges
provided by shearing also enhances computer aided design and
manufacturing (CAD/CAM).
BRIEF SUMMARY OF THE INVENTION
The instant invention is particularly directed to the method and
apparatus for automated handling of panels comprising a plurality
of interconnected substrates in order to control and separate the
circuit boards in a continuous processing line. One embodiment
incorporates two shearing stations and a rotary transfer device
therebetween in order to transfer a panel portion from the first
station to the second station while controlling and rotating the
panel for subsequent feed to the second station such that the panel
portion is cut on a line of the substrate which is perpendicular to
the original line of cut of the substrate. Throughout the handling
of the panels and panel portions, sensing, gripping, and indexed
feeding of the panels and panel portions are under the control of a
programmable computer.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a first embodiment of the
invention.
FIG. 2 is a front elevation of the device of FIG. 1.
FIG. 3 is a top plan view of the input conveyor assembly.
FIG. 4 is a side elevation of the input conveyor assembly.
FIG. 5 is a partial top plan view as viewed generally in the
direction of arrows 5--5 of FIG. 4.
FIG. 6 is a top plan view of the input feed assembly.
FIG. 7 is a front elevation of the device of FIG. 6.
FIG. 8 is a partial left side elevation of the device of FIG.
7.
FIG. 9 is a partial, enlarged view, with portions thereof in
section, in order to illustrate various operational features of the
clamping assembly.
FIG. 10 is a partial elevational view, as viewed from the output of
the machine, in order to illustrate the support and operation of
the moveable shearing blade.
FIG. 11 is a partial cross sectional view which has been enlarged
to illustrate the shearing blades and guard assembly relative to a
circuit board.
FIGS. 12 and 13 are detail drawings illustrating a particular
arrangement of the moveable cutting blade relative to the fixed
cutting blade in order to overcome a particular problem of the
prior art.
FIG. 14 is a side elevation of the output conveyor assembly.
FIGS. 15A-15C are partial top plan views illustrating the passage
of a panel from the input conveying system through the feed
assembly and into position at the shearing station.
FIGS. 16A-16D are schematic side elevational views illustrating
board sensing, gripping, and feeding by the clamping assembly as
well as ejection of scrap material upon completion of shearing.
FIG. 17 is a partial top plan view of a second embodiment of the
instant invention.
FIG. 18 is a front elevation of the embodiment of FIG. 17.
FIG. 19 is an enlarged fragmentary view of the pivotal frame
supporting the shuttle assembly of the second embodiment.
FIGS. 20-23 are partial top plan views illustrating handling of a
panel portion by the rotary transfer assembly of the second
embodiment, from pickup of the panel portion after a first shearing
operation through rotating and feeding the panel portion for a
subsequent shearing operation.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 2 for an overall view of one embodiment of
the instant invention, it may be seen that the apparatus comprises
an input conveyor assembly 10 which feeds circuit board panels to a
feed assembly 40 at which they are gripped and controllably fed
into position for shearing by shearing assembly 90, whereupon the
separated circuit boards are transferred therefrom by means of an
unloading conveyor 130.
A better understanding of the invention may be gained by continuing
to refer to FIGS. 1 and 2 during the following description of the
remaining, more detailed drawings.
Referring to FIGS. 3 and 4, an input conveyor assembly 10 comprises
a frame 12 fixably attached to a main frame 8 of the overall
machine in order to support board guiding side rails 16 during
conveying of the boards by means of chain 21 to a feed assembly 40.
Conveyor chain 21 is driven by motor 22 and drive shaft/sprocket
arrangement 24 (best seen in FIG. 3). The conveyor chain 21 and
guide rails 16 are laterally adjustable to accommodate various
widths of circuit board panels 2, and guide rails 16 extend beyond
the ends of conveyor chain 21 to a position adjacent the front of
shearing assembly 90.
Cooperating with the input or upstream portion of conveyor assembly
10 are optical detectors, with optical detector 32 sensing the
front edge of a panel being fed by the conveyor, so as to initiate
actuation of locator/delay pin 26 such that a panel is properly
positioned for sensing coding notches or the like by optical
detectors 34. By provision of the code sensing arrangement, an
appropriate program may be selected automatically in order to
control operation on a particularly configured circuit board array
of panel 2 during feeding and shearing.
Referring to FIG. 4, the phantom line 55 represents the top surface
of feed assembly rails 54 (of FIG. 1) and, as illustrated, surface
55 is lower than the top run of conveyor 21 in order to facilitate
subsequent clamping and indexed feeding of the circuit board by a
clamping assembly. A timing belt and sprocket arrangement 38 (FIG.
5) provides drive to rollers 36 which are in line with each
conveyor chain 21. These rollers 36 have a frictional board
engaging periphery of rubber or the like, so as to gradually lower
the boards or panels 2 from the top run of chains 21 onto slide
rails 54 via frictional engagement with the rollers 36.
For ease of conveying the circuit boards by conveyor chains 21,
panels 2 are rather loosely guided by rails 16, so that, upon
passing to slide rails 54 of feed assembly 40, panels 2 must be
aligned properly for the clamping assembly and proper feeding to
the shearing assembly. In order to so align the panels, a justifier
plate 37 (FIGS. 4 and 5) comprises a portion of one of the guide
rails 16 and is displaceable transversely to the direction of feed
of the boards so as to square one edge of the panels against the
opposite guide rail 16.
Feed assembly 40 is illustrated in FIGS. 6-8 and comprises a frame
of angle irons 42 pivotally attached to the main frame 8 by rod 44
on the upstream end of feed assembly 40. Supported by frame 42 are
a pair of Thompson shafts 46 along which a shuttle 56 is
reciprocatable via actuation of a lead screw 48 which is also
supported by frame 42. Lead screw 48 is driven via servomotor 50
and encoder 51 in order to provide drive and tracking of the
shuttle 56 during such reciprocation. Shuttle 56 in turn supports
transverse rods 58 along which clamp assemblies 60 are adjustable
according to the circuit board panel being handled. The downstream
end of feed assembly 40 is freely supported upon main frame 8 and
elevated therefrom by actuation of cylinder 52, for a "bumping"
action yet to be described.
Referring to FIG. 9, clamping assembly 60 is supported on
transverse guide rods 58 of shuttle 56 (FIGS. 7 and 9) and
comprises a base 62 to which fixed clamp portion 70 is attached by
machine screws 75. Fixed clamp portion 70 includes fixed jaw 71
cooperable with tapered pin 68 of pivotal jaw 66 during clamping.
Jaw 66 pivots about rod 67 during extension and retraction of
piston rod 65 by cylinder 64, and rod 72 acts as a stop for pivotal
jaw 66 in the retracted positon of piston rod 65. With the
apparatus of the instant invention, no additional holes are
necessary in the printed circuit board panel other than holes which
are normally provided for handling by the circuit board
manufacturer. These tooling holes 7 in the panels 2 are utilized as
positional central references by the method and apparatus of the
instant invention in order to properly orient and grip the panel 2
for subsequent feeding to shearing assembly 90. An optics system
comprising transmitter 76 and receiver 78 is incorporated into
clamping assembly 60, as seen in FIG. 9, with transmitter 76
situated in pivotal jaw 66 and receiver 78 located on the tip of a
support rod 79 depending from base 62. When the clamping cylinder
retracts rod 65, an optics path may be completed through each
tooling hole 7 of circuit board panel 2, with fixed jaw 71
appropriately cut away to allow passage of light beam 77. For the
situation where tooling holes 7 of the circuit board panel 2 are
provided in a scrap portion of the panel and the scrap portion
remains in clamp assembly 60 after the remainder of the panel has
been removed by separation of the individual circuit boards, an
ejector is provided to propel the scrap portion through the
separated shearing blades so that a scrap diverter 124 may guide
the scrap portion to fall along path 126 into scrap bin 128 (FIG.
2). The ejector comprises a pusher 89 at the end of a rod 87
actuatable by cylinder 86, with a guide rod 88 for pusher 89. In
order to ensure that both tooling holes 7 have been accurately
gripped in the spaced pair of clamp assembies 60, a verifier optics
system 80 cooperates with plate 82 having a slot 84 therein, with
plate 82 being clamped to piston rod 65 of clamp cylinder 64 so as
to reciprocate therewith. When proper clamping has been achieved by
a clamp 60, slot 84 will be positioned so as to allow an optics
path to be completed by optic system 80. The optics system 80 must
be properly completed on both clamp assemblies 60 in order for the
feeding process to proceed. If the panel 2 has not been properly
gripped by one or both of the clamp assemblies 60, then both clamps
will be opened and, according to controller 9, shuttle 56 will be
returned to its original upstream position so that the clamping
procedure may be reinstituted.
With a panel properly gripped by both clamp assembies, the panel is
fed forward via driving of shuttle 56 along lead screw 48 according
to the program previously selected during sensing of the board by
code detectors 34. When handling panels previously populated with
components, there is sometimes a slight warp in the plane of the
panel after soldering the component leads by a wave soldering
machine or the like. To overcome any feeding problems due to
warping of the panel, a board guide flap 18 is provided on the
downstream end of each guide rail 16, with the flaps 18 each being
pivoted at points 19 and biased to the downward position by spring
plungers 20. A further problem which may be encountered when
dealing with panels which have already been populated with
components 4 is caused by lead tips 6 which extend below the bottom
surface of panels 2, as illustrated in FIG. 16A. In order to
prevent any interference to feeding of the boards that such
depending lead portions may cause with lower fixed shear blade 116
during feeding of the unsheared panel into position between the
blades of the shear assembly, the downstream end of feed assembly
40 may be "bumped" up by cylinder 52 (FIG. 7), thus providing
clearance between lead portions 6 and fixed shearing blade 116
during positioning of the panel 2 for shearing.
Referring to FIG. 10, shearing assembly 90 comprises an upper
support portion 92 and a pair of lower support portions 94 for a
pair of pillars 96 along which the moveable blade holder 108 is
reciprocatable according to actuation of a drive cylinder 102.
Upper support 92 has a bushing 106 therein to provide rigidity to
piston rod 104, and blade support 108 has bushings 100 within which
bearing sleeves 98 are provided to telescope on pillars 96, also
providing rigidity to the moveable blade assembly. Thus, blade
holder 108 does not wobble, as sometimes would happen in an earlier
prototype, when a circuit board is off-center of the feedpath
through the shear assembly. As seen in FIG. 11, the upstream side
of the shear assembly has a clamping guard 112 which is spring
biased downwardly to engage and clamp panel 2 prior to engagement
by blade 118 so that panel 2 is adequately clamped for the shearing
action. Referring to FIG. 12, it may be seen that the moveable
blade assembly comprises the holder 108 and a pair of blades 118
mounted thereon in an inverted "V" arrangement so that the outer
edges of the board are engaged by the cutter before the inner
portion thereof to prevent slippage of the board sideways during
cutting.
A schematic cross-sectional view through the moveable cutting
blade, as viewed from the top (FIG. 13), illustrates that the two
blade portions 118 have been tapered so that the middle portion
thereof is spaced further than the outer portions from cutting edge
116 of the fixed blade. It has been found, without such a taper and
according to the particular thickness and composition of the
circuit boards to be sheared, that sometimes the blade 118 would
flex and overlap fixed blade 116 during the initial cutting action,
causing a fast recovery of the flexed blade 118 upon full closing
of the shear assembly and resulting in a poor cut (sometimes
breaking) of the board near the mid-portion of the blade assembly.
The structural configuration of FIG. 13 eliminates this problem by
allowing for such flexure of blade 118 so that a clean shearing
action all across the face of fixed blade 116 occurs upon flexure
of blade 118.
In a prototype of this embodiment, the distance "d" that would
provide for proper shearing action under flexure of blade 118 was
found to be 0.004 inches.
Referring to FIG. 14, an unload conveyor assembly 130 receiving
separated circuit boards from the shearing assembly 90 comprises a
frame 132 which is pivotally attached to the main frame of the
machine at 134. Similar to the input conveyor, output conveyor 130
has width-wise adjustable guide rails 136 and conveyor chains 138.
A motor/sprocket arrangement 140 provides drive for the conveyor
chains 138, and a rear conveyor assembly 130 also has a "bump"
function provided, although for a reason different from that of the
input feed mechanism 40. The upstream end of output conveyor frame
132 is freely supported upon main frame 8, with a cylinder 142 for
lifting the upstream end of frame 132 from main frame 8. This
"bumping" function is provided on the output conveyor assembly 130
in order that scrap portions 3 of the panels 2 may pass under the
upstream end of output conveyor 130 into a scrap bin 128, while
normal unloading of printed circuit boards from the shear assembly
90 does not require actuation of "bumping" cylinder 142.
In a typical operation of the above described embodiment,
locater/delay pin 26 is normally in the raised position to stop
forward feed of a panel 2 by conveyor chains 21. A front edge
detector 32 notifies the controller 9 that a panel 2 is in position
for identification, whereupon conveyor chains 21 are halted in
order to prevent unnecessary rubbing of the conveyor chains across
the conductive portions on the bottom of panel 2. Then, panel 2 is
optically sensed by code detectors 34 which sense particular
notches in panel 2 or, alternatively, by a bar code reader
detecting a particular bar code upon the panels 2. Having
identified the board, the pneumatically actuated locater/delay pin
26 is lowered and the appropriate program is activated in
accordance with identification of the board. When the feed assembly
40 is appropriately positioned for acceptance of a panel 2 from
conveyor assembly 10, conveyor chains 21 are driven to carry the
panel 2 forward, over and past the clamp mechanism 60 until panel 2
drops onto the slide racks 54 of feed mechanism 40, from which
there is no further advancing to the shear assemby 90 until panel 2
is properly clamped in clamping assembly 60.
In order to ensure proper alignment of the panel for proper
gripping by clamping assemblies 60, justifier panel 37 engages one
edge of panel 2 and pushes it against a reference surface of the
opposite guide panel 16. Thereafter, the shuttle 56 is advanced by
actuation of lead screw 48 to carry the open clamped assemblies 60
forward in a function of searching for the positional control
reference holes 7, during which the optics path 77 is interrrupted
by the edge of panel 2 and recompleted upon proper location of each
clamp assembly relative to a tooling hole 7 of panel 2. When a
clamp assembly 60 locates a corresponding hole 7, clamp cylinder 64
is fired and moveable clamp jaw 66 is pivoted such that a tapered
pin 68 of the actuated clamp 60 enters the tooling hole 7 to effect
gripping of the panel. An advantage of tapering pins 68 is that
they are self centering when entering holes 7 so that the of
tooling hole 7 placement tolerances of circuit board manufacturers
may be easily accommodated.
The verifier optics system 80 on each clamp assembly 60 senses
proper or improper engagement of pin 68 with each hole 7 of the
panel 2. In the event that only one clamp assembly 60 is properly
holding panel 2, both clamp assemblies will be opened and shuttle
56 will be totally retracted to the home position and the procedure
will be retried a particular number of times before shut-down of
the machine and notification of an operator.
Having properly gripped the panel 2 in clamping assemblies 60, the
board is advanced into shearing assembly 90 according to the
program corresponding to the particular board configuration. During
such feeding, the downstream end of feed assembly 40 is "bumped" up
in order that lead portions 6 on the underside of panels 2 will
clear fixed shearing blade 16 and a particular line of cut for the
circuit panel 2 has been located over fixed cutting blade 16. At
this time, feed assembly 40 is lowered such that the panel is
supported on the line of cut by fixed blade 116, and thereafter,
the shearing function is performed. The height to which the
moveable blade 118 is raised to accommodate the thickness of the
panel and any components mounted thereon is also controlled by the
selected program. For any cut which will produce scrap material on
the output side of shear assembly 90, the unload conveyor assembly
130 is "bumped" up by actuation of cylinder 142 such that the scrap
produced will pass under the upstream end of unload conveyor
assembly 130 and by diverted to a scrap bin 128. For the output of
separated printed circuit boards, the output conveyor remains in
its normal lowered position and, after the cut is completed, the
output conveyor drive is activated to carry the separated circuit
board to an unloading point. For a given panel configuration,
appropriate sequencing will continue until the last board has been
separated from the panel matrix. At this time, the clamps open and
any scrap at the trailing edge of the panel is propelled from the
clamp assemblies 60 through the open jaws of shear assembly 90 by a
pneumatically operated pusher 89.
The upper and lower blades of shear assembly 90 are adjustable in
order to maintain accurate tolerances across the width of the cut,
with moveable blade 118 having the particular configurations
described earlier in reference to FIGS. 12 and 13.
Shearing assembly 90 also incorporates an optics guard system (not
shown) comprising an infrared modulated beam positioned 0.187
inches above and 0.025 inches behind the cutting line to prevent or
abort a cutting stroke if anything obstructs the blade path, with
an override being activated by a gray code bar once the blade
enters the light beam path. Operating parameters of the shear,
namely shear clearance (upper limit), stroke length, and lower
limit, are set and controlled by a remote control unit for the
shear or by the main controller. Feedback regarding status of the
shear operation vis-a-vis stored parameters is provided by
stationary optic sensors interacting with a gray code bar which is
attached to the moveable blade and follows its movements.
FIGS. 17-23 illustrate an alternate embodiment of the instant
invention which provides for dual-axis profiling of separating of
circuit boards from the panel in a two-stage shearing process. This
alternate embodiment incorporates the features of the earlier
described embodiment with the additions of a rotary transfer
assembly for receiving boards from the first stage shear assembly
and a second stage shear assembly to which the boards are presented
by the rotary transfer assembly. The output conveyor assembly of
the earlier embodiment may then follow the second stage shear
assembly or, alternatively, other types of off-loading systems such
as a robot arm may receive the separated boards on outputting
thereof from the second shear station.
In several of the figures, details of the shearing assembly have
been omitted in order to provide a better view of the transfer
assembly, while indicating the lines of cut 220, 230 respectively,
for the first and second stage shears. The shearing assemblies are
substantially the same as the earlier described shearing assembly
90, with the first stage shearing assembly being reversed to allow
closer approach thereto by transfer assembly 150.
Rotary transfer assembly 150 comprises a frame 152 (best seen in
FIG. 19) which is pivotally supported at 156 to the main frame of
the overall machine. A spring 162 is provided under the free end of
rocking frame 152 which is closest to the first stage shear
assembly, and a "bump" actuating cylinder 158 is provided beneath
the end of rocking frame 152 at the second stage shear assembly.
Additionally, spring plungers (not shown) may be located at the end
of rocking frame 152 closest to the second stage shear assembly to
oppose the bias of spring 162 and provide a counterbalancing force
for a purpose yet to be described.
Frame 152 supports Thompson shafts 154 along which a shuttle 170 is
reciprocatable via a drive motor 172 and chain assembly 174.
Shuttle 170 rotatably supports a table 180, with rotation being
imparted to the table via a cam plate 164 and cam follower 182
during reciprocation of the shuttle 170 back and forth between the
first and second stage shear assemblies. Cam follower 182 and table
180 are attached via a shaft 183 and offset arms thereon, with the
shaft 183 being rotatably supported by a bearing of shuttle 170,
such that camming plate 164 is located below shuttle 170 and
receives cam follower 182 therein to guide rotation of table 80
during reciprocation of shuttle 170. Also attached to shaft 183, by
offset arms or the like, are suitable stop plates engageable with
adjustable stops on the underside of shuttle 170 to provide
adjustable limits of rotation for rotary table 180. Adjustable
stops for reciprocation of the shuttle 170 may also be provided as
needed.
Rotary table 180 has Thompson shafts 184 along which a board
gripping assembly 190 is reciprocatable according to a lead screw
186, and servomotor 188, with an encoder 189 enabling positional
control of the gripping assembly 190 along Thompson shafts 184.
Gripper assembly 190 comprises a fixed lower plate 192 cooperable
with grippers 196 located on pivotal support rod 194. Grippers 196
are adjustably positionable along rod 196, as by keying or the
like, and are hard tapered pins which bite into the surface of the
circuit board during such gripping. An actuating cyclinder 202 is
connected to support rod 194 via angle arm 200 to supply a total
gripping force of approximately 180 pounds distributed between
selected pins 198 which are gripping a board at the time. In order
to properly grip a board, there must be a component-free zone of
the substrate material for clearance of the pins during gripping.
Such a component-free zone may comprise a portion of the circuit
board itself or a scrap portion of the substrate material. For the
case in which the pins are engaging a scrap portion of substrate,
an ejector plate 204 is provided to reciprocate between the pins
198 and fixed lower plate 192 with a force sufficient to eject
scrap material therefrom and through the second stage shear
assembly.
In operation of this second embodiment, a panel of material is
advanced into the first stage shear assembly 90 in accordance with
the earlier described embodiment. With the panel in position for
the first cut, the shuttle 170 is moved to the first stage shear
assembly and the portion of the panel extending through the shear
assembly is gripped by board gripper assembly 190 prior to
shearing. By the provision of pivotal support 156 and spring 162,
the panel section in the grasp of gripping assembly 190 may be
displaced downwardly by the first stage shearing action without
flexing inordinately and damaging the traces or solder joints of
the circuit board. Once this first cut has been performed, the
shuttle 170 will be driven to the second stage shear assembly 210
and, during such drive, rotary table 180 will be rotated 90.degree.
in accordance with the cam follower 182 and camming plate 164.
Thereafter, the portion of the panel which is gripped by gripping
assembly 190 is advanced into the second stage shear assembly 210
via lead screw 186 and motor 188, in accordance with control by the
preselected program.
The downstream end of frame 152 is raised by "bumping" cylinder
158, when dealing with circuit boards that have already been
populated, in order to clear the lead tips over the fixed blade of
the shear assembly during positioning for the second cut. Frame 152
is lowered when the panel is accurately positioned in the second
stage shear for cutting.
In operation, if the first cut will produce scrap material at stage
one, the transfer shuttle 170 is moved away from the first stage
shear assembly sufficiently for scrap material to drop and be
diverted to a scrap box 128. Then, shuttle 170 is moved back to the
first stage shear assembly and gripping assembly 190 is actuated to
grip the portion of a panel 2 which is extending through shear
assembly 90. Thereafter, the first cut is made with rocking frame
152 displacing against the bias of 162 during the cut to allow the
panel section to drop slightly during shearing without undue
flexure and mechanical shock. Rotary transfer assembly 50 then
transfers the severed panel portion to the second stage shearing
assembly, with rotation of this portion of the panel being provided
during such transfer. During the transfer, the downstream end of
frame 152 is raised by cylinder 150 in order to provide clearance
for the lead tips on the underside of the circuit board when
advanced into the second stage shearing assembly. Upon shuttle 170
arriving at second stage shear assembly 210, clamping assembly 190
is advanced across table 180 via lead screw 186 and motor 188 to
position the board for the second axis cut, and the downstream end
of frame 152 is lowered upon achieving proper positioning of the
board and prior to the cut. After the cut, an unload conveyor (as
described in the earlier embodiment), a robot arm, or the like may
be used to unload the finished circuit board from the second stage
shear 210. When necessary, the gripping assembly 190 ejects any
scrap through the open second stage shearing blades and is returned
to the first stage shearing assembly via retraction along lead
screw 188 and movement of shuttle 170 back to the first stage
shearing assembly. Thereafter, the cycle is repeated until the last
circuit board has been separated from the panel matrix.
As is discernable from FIGS. 22 and 23, a panel portion which has
been positioned for cutting at the second stage will often be
offset to one side of the second stage shear assembly. Accordingly,
a particular arrangement of the shearing blades 118 and their
angling relative to the lower fixed blade in the second shearing
assembly may be modified in order that the particular boards being
handled in the second stage shear assembly will still be engaged on
opposite sides thereof by an angled blade to keep the boards from
moving transverse to the line of feed through the shear
assembly.
Although particularly directed to separating populated PCB's from
multi-board panels, it is contemplated that the invention is also
useful in separating unpopulated boards. It is also contemplated
that either of the clamping or gripping assemblies may be used for
both board holding functions or may be interchangeable with each
other. It is further contemplated that the above-noted processing
may be printing, such as bar coding, or silk screening before or
after population and in conjunction with, before, after, or
separate from subdividing of the panel.
It will thus be seen that the objects of the invention, among those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in carrying out the
above constructions without departing from the spirit and scope of
the invention, it is intended that all matter contained in the
above description or shown in the accompanying drawing shall be
interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described, and all statements of the scope of the invention,
which, as a matter of language, might be said to fall
therebetween.
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